EP0300270B1 - Latch arrangement for a high-speed circuit breaker - Google Patents

Abstract

A release mechanism for a high speed circuit breaker comprises a roller rotatably supported on an axle in a mobile contact bridge. A jack is acting in the circuit closing direction on the roller, and the frontal side of the jack is in the form of a slide. The force of a disconnecting spring acts on the contact bridge in a disconnecting direction. The release mechanism to be provided with the connected contact bridge is capable of very rapid release, so that high short circuit currents may be interrupted very rapidly. This is obtained by the slide having a configuration such that in the connected state of the contact bridge the frictional forces acting on the roller are compensated.

Description

TECHNICAL AREA

The invention is based on a latch for a quick-action switch according to the preamble of claim 1.

STATE OF THE ART

From US-A-3 864 649 a quick switch is known which has a pawl acting on a movable contact via a roller. The side of the pawl facing the roller is somewhat adapted to the roller contour. The movable contact is acted upon by a spring in the opening direction, but the pawl prevents the opening movement of the contact when switched on. As soon as the pawl is actuated by a trigger, it releases the opening movement of the contact. The pawl must be moved completely sideways so that the roller and thus the contact movement is released.

From US-A-2031 458 a latch is known which converts the response of an electrical trigger into an actuation of a switching element connected downstream. In this latching, the pawl acts against a roller of a spring-loaded lock, the torque exerted by the force actuating the pawl should be approximately the same as the torques generated by frictional forces, which prevent the pawl from moving.
A latching device for a high-speed switch is known with a roller rotatably mounted on an axis in a movable contact bridge. When switched on, a ratchet rod actuated by a magnet acts on the roller, presses the contact bridge against a fixed contact and thus closes the circuit with the quick switch. The necessary contact force is also provided by the magnet via the latch rod transferred to the role. When the quick switch is switched off normally, the magnet is de-energized and a pre-tensioned switch-off spring that also acts on the roller pulls the contact bridge into the switch-off position. The arc that occurs is extinguished in a known manner. However, if a short-circuit current flows through the quick switch, this normal switch-off takes too long and a trigger that is actuated directly by the short-circuit current is excited. This trigger acts on the latch rod and ensures that the latch between the roller and the latch rod is released. The switch-off spring acting on the roller then takes effect immediately and the contact bridge is quickly pulled in the switch-off direction.

The trigger acting on the ratchet rod, for example a trigger magnet, must be of strong dimensions in order to be able to move the ratchet rod safely relative to the roller, since large opposing forces have to be overcome. If the trigger is designed to be somewhat weaker, the switch-off time is increased to impermissible values.

PRESENTATION OF THE INVENTION

The invention seeks to remedy this. The invention, as characterized in the claims, solves the problem of creating a latch for a switched-on contact bridge of a high-speed switch that can be released very quickly, so that high breaking currents, in particular short-circuit currents, can be interrupted particularly quickly.

The advantage achieved by the invention is essentially to be seen in the fact that immediately after the release of the latch, a component of the force still acting on the roller in the switch-on direction additionally accelerates the movement of the latch rod and thus enables an even faster switch-off movement of the contact bridge.

The further developments of the invention are the subject of the dependent claims.

The invention, its further development and the advantages which can be achieved therewith are explained in more detail below with reference to the drawings, which only represent an embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

• Fig. 1 eine Prinzipskizze eines Kontaktsystems eines Schnellschalters,
• Fig. 2 eine Detailskizze der erfindungsgemässen Verklinkung, und
• Fig. 3 eine Darstellung der in der Verklinkung nach Fig. 2 wirksamen Kräfte.

Show it:

• 1 is a schematic diagram of a contact system of a quick switch,
• 2 shows a detailed sketch of the latch according to the invention, and
• Fig. 3 shows the forces acting in the latch according to Fig. 2.

Elements with the same effect are provided with the same reference symbols in all the figures.

WAYS OF CARRYING OUT THE INVENTION

In Fig. 1, a contact system of a quick switch is shown in a highly simplified manner. A fixed contact 2 is fastened to a busbar 1. In the switched-on state, a movable contact piece 3 is pressed onto the fixed contact 2 and is connected to one end of a movable contact bridge 4. The other end of the movable contact bridge 4 is rotatably mounted in a roller bearing 5 which is suitable for carrying the current. This roller bearing 5 is embedded in a busbar 6. The components 1 to 6 described so far form the main circuit of the high-speed switch. During the switch-off process, when an arc burning between the fixed contact 2 and the contact piece 3 commutates in a known manner on spark horns 8 and 9, one is briefly Secondary flow path 10 is supplied with current. The contact bridge 4 is then no longer supplied with current and runs into its switch-off position without further electrical stress. As soon as the arc, which jumps in a known manner from the spark horns 8, 9 onto a large number of quenching plates (not shown), is extinguished, the current flow through the quick switch is definitely interrupted. The recurring voltage is then present between the fixed contact 2 and the contact piece 3.

The contact bridge 4 has an opening 12 extending in the direction of its longitudinal axis. Side walls of this opening 12 carry an axis 13 on which a cylindrical roller 14 is rotatably mounted. The axis 13 and the roller 14 have a common central axis which runs perpendicular to the direction of movement of the contact bridge 4. In the switched-on state of the contact bridge 4, the roller 14 rests on a latch rod 15, the end face of which facing the roller 14 is designed as a slotted link 16 which is at least partially adapted to the roller contour. The end of the pawl rod 15 facing away from the roller is rotatably mounted in an insulating part 17. A connecting piece 18 connects the insulating part 17 to a switch-on and switch-off device which is known in principle and which is not shown. A spring 19, which is supported on a support 20 made of insulating material, presses the pawl rod 15 upward against the roller 14. The on and off device acts on the roller 14 and thus on the contact bridge 4 via the pawl rod 15. In the switched-on state, it also applies the contact force between the fixed contact 2 and the contact piece 3, any contact erosion is automatically compensated for in the process.

The forces which act on the contact bridge 4 in the switch-on direction are applied by the switch-on and switch-off device. For a normal, operational switch-off, the force in the switch-on direction is released and a switch-off spring 22, which acts directly on the contact bridge 4, pulls the same into its switch-off position. The opening spring 22 is insulated at least on one side to prevent stray currents from the opening spring. If very large currents, for example short-circuit currents, are to be switched off, the switch-off process must be accelerated. An additional trigger 25, for example a magnet, which is directly excited by the high current, acts by means of a pawl 26 on the end 27 of the pawl rod 15, which projects through the opening 12. The pawl rod 15 is pressed down and the roller 14 rolls along the backdrop 16 in the switch-off direction. The latching between roller 14 and latch rod 15 is released very quickly in this way.

To explain the mode of operation of this latch, FIG. 2 is first considered in more detail. The end face of the latch rod 15 designed as a backdrop 16 is partially adapted to the roller contour. From a point A, the part of the link 16 adapted to the roll contour merges into a section running tangentially to the roll 14. The link 16 is designed such that when the contact bridge 4 is switched on, the friction forces acting on the roller 14 are compensated for. The section of the link 16 running tangentially to the roller 14 is inclined at an angle of 90 ° -α with respect to the switch-on direction. The switch-on direction is indicated by an arrow 28. The angle α itself is defined as the angle between the switch-on direction and the connecting line 29, which connects the point A with the center Z of the axis 13. The same angle α also occurs as the angle between the section of the link 16 running tangentially to the roller 14 and a line running perpendicular to the switch-on direction of the latch rod 15. The section of the link 16 which runs tangentially to the roller 14 does not have to run straight up to the upper edge of the latch rod 15, it can also be rounded somewhat, as indicated by a broken line 30, in order to facilitate the running of the roller 14.

dargestellt werden kann, senkrecht zur Komponente P₂. Die Komponente P₃ kann parallel verschoben werden, bis ihre Wirkungsrichtung mit der Richtung des tangential verlaufenden Abschnitts der Kulisse 16 zusammenfällt. Sie wirkt dann von oben her auf den Punkt A ein. Dieser Kraftkomponente P₃ wirkt eine genau gleich grosse Kraft P₄ auf der gleichen Achse entgegen. Diese Kraft P₄ ist die Summe der Reibungskräfte, die in dem System Achse 13, Rolle 14 und Kulisse 16 auftreten.From Fig. 3, the essential forces can be seen, which are effective at point A between roller 14 and jack rod 15. A force P₁ acts in the switch-on direction, it is by the Applied on and off device. This force P₁ can be broken down into its components P₂ and P₃ in a known manner. The component P₂ acts in the direction of the center Z of the axis 13 and the component P₃ by the relationship $\text{P₃ = P₁ · sinα}$

can be represented, perpendicular to component P₂. The component P₃ can be moved in parallel until its direction of action coincides with the direction of the tangential portion of the link 16. It then acts on point A from above. This force component P₃ counteracts an exactly equal force P₄ on the same axis. This force P₄ is the sum of the frictional forces that occur in the axis 13, roller 14 and link 16 system.

bestimmt, wobei C₆ der Reibungskoeffizient zwischen Rolle 14 und Kulisse 16 ist. Die Reibungskraft zwischen Achse 13 und Rolle 14 wird im Verhältnis des Radius R₁ der Achse 13 zum Radius R₂ der Rolle 14 verkleinert. Im Punkt A wirkt von dieser letzteren Reibungskraft die Komponente

The friction force P₄₁ that occurs between roller 14 and link 16 through the relationship $\text{P₄₁ = P₁ · cosα · C₆}$

determines, where C₆ is the coefficient of friction between roller 14 and link 16. The frictional force between axis 13 and roller 14 is reduced in the ratio of the radius R₁ of the axis 13 to the radius R₂ of the roller 14. At point A, the component acts from this latter frictional force

bestimmt.The force P₄ is due to the relationship $\text{P₄ = P₄₁ + P₄₂}$

certainly.

If the component P₃ and the force P₄ are equated to each other, the following equation results for the dimensioning of the angle α:

The roller 14 can have an outer running surface into which a groove-shaped recess is embedded. This recess serves as a guide for the end face of the pawl rod 15. The pawl rod 15 slides sideways from the roller 14 is avoided. Tilting of the two parts is also avoided. Furthermore, it is possible to adapt the end face of the latch rod 15 to the shape of the recess in the roller 14 in order to obtain an even better guidance.

Claims (3)

1. Latch for a high-speed circuit breaker, having a roller (14) which is supported in a moving contact bridge (4) such that it can rotate on a shaft (13), having a latching rod (15), which acts on the roller (14) in the switching-on direction and is supported such that it can rotate and whose end facing the roller (14) is constructed as a link (16) which is matched at least partially to the roller contour, having a force which acts on the contact bridge (4) in the switching-off direction and is applied especially by a spring element (22), and having a trip device (25) which acts on the latching rod (15), characterised in that the link (16) is constructed such that, in the switched-on state of the contact bridge (4), the friction forces acting on the roller (14) are compensated for, which is achieved in that the part of the link (16) which is matched to the roller contour merges into a section which runs tangentially with respect to the roller (14), and in that the section of the link (16) which runs tangentially with respect to the roller (14) is inclined through an angle of 90°-α with respect to the switching-on direction, the angle α being dimensioned as follows:

   

   C₅ in this case being the coefficient of friction between the shaft (13) and the roller (14), C₆ the coefficient of friction between the roller (14) and the link (16), R₁ the radius of the shaft (13) and R₂ the radius of the roller (14).
2. Latch according to Claim 1, characterised in that the running surface of the roller (14) has a recess which is used as a guide for the end of the latching rod (15).
3. Latch according to Claim 2, characterised in that the end of the latching rod (15) is matched to the shape of the recess.

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